It is necessary that the winding procedure for winding yarns or threads, especially synthetic threads, should be effected at a constant winding speed. Any alteration in this speed produces blemishes during the processing of the thread up to the finished product. Thus, it is usual to drive the thread package at the periphery thereof by a friction or pressure roller. The rotational speed of the motor remains constant and continues to be unrelated to the increasing diameter of the thread winding. When the shaft of the thread package is driven, complicated control systems are required to adapt the rotational speed of the shaft to the increasing diameter of the thread package to achieve the uniform peripheral speed of the package.
Difficulties frequently occur with the friction drive at high winding speeds such as 6000 to 7000 meters per minute and above. During this starting phase of such a winding procedure, the mandrel and the bobbin tube cannot be brought rapidly enough up to the required rotational speed. Slippages occur between the synchronous motor having an external rotor which rotates at constant speed and the bobbin tube located on the mandrel. The slippages can be so large that the bobbin tube is damaged during the start of the winding procedure. Frequently, the initial thread layers in the thread package are seriously damaged because of the lack of synchronism between the friction drive and the thread package.
The prior art has attempted to eliminate this disadvantageous slippage by changing the association between the friction drive and the axial drive of the mandrel. For example, it is known to use a gas turbine run with compressed air for effecting the axial drive of the mandrel. There must be a reduction in the moment to be brought into the axial drive in conformity with the decreasing angular velocity with increasing thread package. The supply of gas pressure must be controlled through a pressure control device operating in conjunction with the gas turbine. In one instance, decreasing support through the gas turbine is maintained until the thread package is completed. In another case, the axial drive is effected only for a certain predetermined period. Once the predetermined diameter of the thread package has been achieved, the axial drive is completely turned off. As long as the axial drive is in operation, however, the pressure of the compressed air for the gas turbine must be constantly reduced to achieve a gradual reduction of the axial driving torque.
The use of these prior art gas turbines is subject to considerable disadvantages. Considerable amounts of compressed air must be used resulting in many disadvantages such as considerable noise which to a greater or lesser degree is sirenlike. The double drive mechanism using a friction roller and a gas turbine for effecting the axial drive of the mandrel furthermore does not show satisfactory results.